This invention is a highly effective method for removing vanadium, nickel, sulfur and asphaltenes from hydrocarbon oil, particularly heavy hydrocarbon oil.
Prior to usage of heavy oil, it is necessary to desulfurize the oil at low cost. Hitherto, desulfurization has been conducted by hydrodesulfurization. This system uses nickel, cobalt and molybdenum deposited on a silica-alumina carrier as the catalysts. Heavy oils contain metals such as vanadium and nickel and sulfur and asphaltene, etc. When such a heavy oil is hydrodesulfurized in the presence of said catalyst, vanadium, nickel and carbonaceous substances contained therein adhere to the catalyst and consequently block the functioning portion or the active site of the catalyst. Accordingly, the catalyst is gradually deprived of its activity, namely the ability to hydrodesulfurize the hydrocarbon oil. Particularly in the case of vanadium, it is well known the length of life of the catalyst is chiefly determined by the amount of this metal deposited on the catalyst. In this respect, methods for removing vanadium and nickel from heavy oil effectively in such a way that the life of the catalyst will be extended have been proposed. For example, Japanese Pat. Publication No. 20914/1971, discloses a method whereby heavy oil containing vanadium and nickel is brought into contact with a vanadium-impregnated activated alumina catalyst in the presence of hydrogen to remove said defiling metals from heavy oil. However, the production of the vanadium-impregnated activated alumina to be used in this method entails a complicated process.